#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
	int i=0;
	double sum=0;
	for (i = 1; i <= 100; i++)
	{
		if (i % 2 == 1 || i == 1)
		{
			sum += 1.0 / (double)i;
		}
		else
			sum -= 1.0/(double) i;

	}
	printf("sum=%lf\n", sum);
	return 0;
}

